A serial device serves a specific purpose, such as gathering and displaying transaction, video and/or control information from an environment where the serial device is installed. Examples of such serial devices are found in retail data systems (e.g., Point-of-Sale (POS)), medical/healthcare systems and building automation/security systems, etc. Typically, a specific application protocol is used for an application program on a host computer to communicate with such a serial device through standard serial ports such as COM and TTY interfaces depending on participating operating systems. For example, RFC-2217, Modus and DF1 are application protocols widely used in industry for such a purpose. On the other hand, custom-defined protocols, such as the RealPort product marketed by Applicant, may be used. When the serial devices are connected to the host computer over a network, an appropriate transport protocol is used to transmit the serial device request from the application program to its associated serial device over the network. For example, Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Telnet and Secure Sockets Layer (SSL) are transport protocols widely used in the industry for such a purpose.
Existing serial port redirectors are dedicated to one application protocol and one transport protocol pair. For example, Modbus ASCII/RTU serial device requests may be paired with TCP. It would be advantageous to allow application protocols to be dynamically paired with transport protocols as needed. In addition, in the existing serial port redirectors, everything that an application sends to the serial port redirector is sent to the serial device. In many of these scenarios, the control data is unnecessary for operation of at least some of the serial devices. The transfer of unnecessary control data over the network increases network costs, especially when the serial port redirector is used in a wireless network that charges according to the amount of information being transferred over the network.
What is needed is a serial port redirector that supports dynamic transition from one application/transport protocol pair to another application/transport protocol pair. In addition, what is needed is a system and method for limiting transfer of unnecessary control information over a network.